Find remainder when $ 2x^{2}+2x-3 $ is divided by $ x+3 $.
Answer
The synthetic division table is:
$$ \begin{array}{c|rrr}-3&2&2&-3\\& & -6& \color{black}{12} \\ \hline &\color{blue}{2}&\color{blue}{-4}&\color{orangered}{9} \end{array} $$The remainder when $ 2x^{2}+2x-3 $ is divided by $ x+3 $ is $ \, \color{red}{ 9 } $.
Explanation
We can find remainder using synthetic division method.
Step 1 : Write down the coefficients of the dividend into division table. Put the zero from $ x + 3 = 0 $ ( $ x = \color{blue}{ -3 } $ ) at the left.
$$ \begin{array}{c|rrr}\color{blue}{-3}&2&2&-3\\& & & \\ \hline &&& \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rrr}-3&\color{orangered}{ 2 }&2&-3\\& & & \\ \hline &\color{orangered}{2}&& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -3 } \cdot \color{blue}{ 2 } = \color{blue}{ -6 } $.
$$ \begin{array}{c|rrr}\color{blue}{-3}&2&2&-3\\& & \color{blue}{-6} & \\ \hline &\color{blue}{2}&& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ 2 } + \color{orangered}{ \left( -6 \right) } = \color{orangered}{ -4 } $
$$ \begin{array}{c|rrr}-3&2&\color{orangered}{ 2 }&-3\\& & \color{orangered}{-6} & \\ \hline &2&\color{orangered}{-4}& \end{array} $$Step 4 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ -3 } \cdot \color{blue}{ \left( -4 \right) } = \color{blue}{ 12 } $.
$$ \begin{array}{c|rrr}\color{blue}{-3}&2&2&-3\\& & -6& \color{blue}{12} \\ \hline &2&\color{blue}{-4}& \end{array} $$Step 5 : Add down last column: $ \color{orangered}{ -3 } + \color{orangered}{ 12 } = \color{orangered}{ 9 } $
$$ \begin{array}{c|rrr}-3&2&2&\color{orangered}{ -3 }\\& & -6& \color{orangered}{12} \\ \hline &\color{blue}{2}&\color{blue}{-4}&\color{orangered}{9} \end{array} $$Remainder is the last entry in the bottom row $ \left(\color{red}{ 9 }\right) $.